Brother NC-2200W Network User's Manual page 18

Network Key (WEP Key)
This key is a 64-bit or 128-bit value that must be entered in an ASCII
or HEXADECIMAL format.
64 (40) bit ASCII:
64 (40) bit Hexadecimal:
128 (104) bit ASCII: Uses 13 text characters.
128 (104) bit Hexadecimal:
Uses 5 text characters.
e.g. "Hello" (this is case sensitive).
Uses 10 digits of hexadecimal data.
e.g. "71f2234aba"
e.g. "Wirelesscomms"
(this is case sensitive).
Uses 26 digits of hexadecimal data
e.g. "71f2234ab56cd709e5412aa3ba"
NC-2200W WIRELESS SETTING 2 - 7